Stainless steel 314, UNS S31400 / W.Nr. 1.4841
Thaida Stainless Steel Manufacturing (Thailand) Co., Ltd., working from Ban Bueng, Chonburi, Thailand, manufactures stainless steel 314 seamless tubes for radiant heating elements, furnace conveyors and heat-treatment equipment that face scaling and carburizing atmospheres. Designated UNS S31400 and cross-referenced to WNR 1.4841, the grade combines 1.50 to 3.00% silicon with high chromium and nickel, giving our stainless steel seamless tubes range a heat-resisting option for oxidizing furnace gas. Our Bang Phli, Samut Prakan team reads each furnace drawing line by line.
Stainless Steel 314 seamless tubeUNS S31400 / W.Nr. 1.4841
EN 10204 3.1 certificate / 3.2 on request
Each SS 314 seamless tube begins as a hot-pierced hollow that is cold drawn or cold rolled to the ordered size, then solution annealed and water quenched before it goes to testing.
No grade row for UNS S31400 exists in ASTM A213 / ASME SA-213, which is written for seamless tubing in boilers, superheaters and heat exchangers. Each UNS S31400 seamless tube is therefore produced to the 314 chemistry and annealed minimums set out below, within the same size envelope as our A213 seamless tubing. If your drawing sizes the material by NPS and schedule instead of OD and wall, we quote it as stainless steel 314 seamless pipe.
Each heat that becomes seamless S31400 stainless steel tube is reported on its own EN 10204 3.1 (3.2 on request) material test certificate. The raw material certificate, solution-anneal charts, a 100% PMI log and a report of measured size and surface roughness are filed with it. When your order lists them, ultrasonic, eddy current or hydrostatic test results and flattening, flare, bend, impact, hardness, grain size, intergranular and pitting corrosion checks are entered on our manufacturer test certificate. Third-party inspection is available on request.
Silicon of 1.50 to 3.00% is the defining addition in 314, with chromium held between 23.00 and 26.00% and nickel between 19.00 and 22.00%. The heat analysis of each melt is reported against these limits.
UNS S31400314
| Element | Lower Limit, % | Upper Limit, % |
|---|---|---|
| C (Carbon) | none | 0.25 |
| Mn (Manganese) | none | 2.00 |
| P (Phosphorus) | none | 0.045 |
| S (Sulfur) | none | 0.030 |
| Si (Silicon) | 1.50 | 3.00 |
| Cr (Chromium) | 23.00 | 26.00 |
| Ni (Nickel) | 19.00 | 22.00 |
Our 314 limits set three ambient-temperature minimums for annealed tube, and the material test certificate reports each heat against them.
| Annealed Property | Minimum Required |
|---|---|
| Tensile strength | 550 MPa / 80 ksi |
| Yield strength | 205 MPa / 30 ksi |
| Elongation | 35% |
Stainless Steel 314 is identified in the US and European numbering systems as listed below.
Read the European entries as cross-references when checking a drawing: a part marked X15CrNiSi25-21 or a seamless WNR 1.4841 tube is checked against the UNS S31400 chemistry above before we quote it.
Compared with stainless steel 310 seamless tubes, grade 314 keeps the same 19.00 to 22.00% nickel and the same 0.25% carbon ceiling, but its silicon of 1.50 to 3.00% sits above the 1.50% maximum of 310, and its chromium band starts at 23.00% rather than 24.00%. Stainless steel 310H seamless tubes hold carbon to 0.04 to 0.10% and silicon to 1.00% max, and need grain size 7 or coarser, the H-grade requirement behind their creep-rupture strength. Grades 314 and 310H share the 1.4841 cross-reference, so a European line that names only that number needs its UNS number before the seamless WNR 1.4841 tube can be quoted.
Grade 314 is produced in ODs between 6.35 mm and 257 mm, walls between 0.89 mm and 12.7 mm, and single lengths reaching 22 m. Small and mid-size tube for radiant elements, conveyor parts and exchanger bundles is held to the same cold-finished permitted variations that govern our A213 seamless tubing:
| OD Band (mm) | Cold-Finished Limit on OD (mm) |
|---|---|
| Below 25 | +0.1 / -0.11 |
| 25 up to and including 40 | ±0.15 |
| Above 40, below 50 | ±0.2 |
| 50 up to, not including, 65 | ±0.25 |
| 65 up to, not including, 75 | ±0.3 |
For 75 mm OD and larger, the diameter limit is stated against each line of the quotation.
Scaling, carburizing atmospheres and repeated heating cycles are the conditions that put seamless stainless steel 314 tube on a furnace drawing.
Seamless 314 radiant tubes pass heat to the furnace load without direct flame contact, spreading it evenly while the high-silicon wall resists oxidation and thermal stress through long heating campaigns.
Furnace conveyor systems on continuous heat-treatment and manufacturing lines are built with 314 stainless steel seamless tube, which carries mechanical load at heat and withstands repeated heating cycles without deteriorating.
Annealing and carburizing boxes made from seamless grade 314 shield components during thermal processing and resist warping, scaling and the carburizing atmosphere inside industrial heat-treatment furnaces.
Trays, baskets and supports cut from 314 seamless tube ride through the furnace with every load, so they must keep their strength and shape through cycle after cycle of heating and cooling.
Chemical processing, oil and gas production and power generation plants use seamless 1.4841 stainless steel tube in heat exchangers where high temperatures and corrosive media act together and steady heat transfer still matters.
Internal and structural furnace members fabricated from SS 314 seamless tube stay in service through prolonged heat exposure, mechanical stress and hostile furnace atmospheres.
Cases
Small-OD and thin-wall tube packed in wooden cases; larger sizes bundled and wrapped.
Identification
UNS S31400, heat number, OD, wall and length stenciled along every tube.
Ends
Plastic caps pressed into both bores of each tube.
Lengths
One piece up to 22 m per tube, or cut lengths matching your drawing.
Sales terms
FOB, CFR or CIF, as written in the quotation.
Export markets
Thailand, Singapore, Malaysia, Vietnam, Indonesia, the Philippines and India.
Stainless steel 314 seamless tubes are quoted indicatively at USD 6.5 to 10.5 per kg. Nickel sits at the level of 310S, while the added silicon and the small number of mills that draw 314 seamless tube, often in small lots, lift the price above that grade; within the band, OD, wall, length and order size set the figure. Send your sizes for a firm price.
Indicative only. Send your sizes and specification to Thaida for a firm quotation.
Piercing through to final inspection of stainless steel 314 seamless tubes is done in one plant, at 154 Moo.1 Map Phai, Ban Bueng, Chonburi 20170, Thailand. Price offers, drawing checks and export documents are prepared by the Thaida sales staff based at 89/18 Moo.15 Enterprize Park, Bangna-Trad Road, Bang Kaeo, Bang Phli, Samut Prakan 10540, Thailand.
Tensile is higher and elongation lower. Grade 314 needs at least 550 MPa tensile strength and 35% elongation, while grade 310 is held to 515 MPa and 40%; the two grades share a 205 MPa yield minimum.
No maximum hardness is set in the 314 limits we produce to: acceptance rests on the tensile, yield and elongation minimums in our strength table. If your specification needs a hardness value, write the figure and test method into the order, and the measured value is listed on our manufacturer test certificate.
No. The cold-finished permitted variations we hold on 314, matching those of our A213 seamless tubing, cover the tube as delivered, before any upsetting, swaging, expanding, bending or polishing. They include out-of-roundness, except on thin-wall and small cold-finished sizes, which follow separate ovality rules. Tolerances for the formed part belong on your drawing.
For its silicon. Grade 314 is held to 1.50 to 3.00% silicon where 309 is capped at 1.00%, and that addition improves resistance to scaling and to sulfur-bearing gases. The nickel band also moves up, from 12.00 to 15.00% in 309 to 19.00 to 22.00%, and chromium from 22.00 to 24.00% to 23.00 to 26.00%.
To restore its corrosion resistance. After the anneal within 1040 to 1150°C, or 1900 to 2100°F, each length is cooled rapidly in water, which leaves the tube in the annealed condition on which our tensile, yield and elongation minimums are based, ready for final testing.
One agreed at quotation. The permitted-variation tables we work to stop at 225 mm OD, while our 314 range reaches 257 mm, so for those sizes the diameter limit is written into the quotation and order confirmation. Up to 225 mm, the cold-finished limit for each size band is fixed in advance.
Request a Quote for Stainless Steel 314 Seamless Tubes
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